Connectivity Fault Management (CFM) is an Ethernet standard defined in IEEE 802.1ag to provide many common Operations, Administration, and Maintenance (OAM) functions associated with underlying network transport for services. For example, CFM allows for the discovery and verification of the path, through 802.1 bridges and LANs. CFM also defines Maintenance Domains, their constituent Maintenance Points, and the managed objects required to create and administer them. CFM defines the relationship between Maintenance Domains and the services offered by VLAN-aware Bridges and Provider Bridges, describes the protocols and procedures used by Maintenance Points to maintain and diagnose connectivity faults within a Maintenance Domain, and provides for future expansion of the capabilities of Maintenance Points and their protocols.
Referring to FIG. 1, a network 100 can include Network Termination Equipment (NTE) 102 at an edge of the network 100 connected to an aggregated head end 104 over a layer two network 106. PseudoWires (PWs) are one type of service that runs between the NTE 102 and the head end 104, and PWs can be used for transporting encapsulated Time Division Multiplexed (TDM) or Asynchronous Transfer Mode (ATM) services, for example. Each PW is identified by a PW label. The PWs run on top of tunnels. The tunnels are identified in the case of 802.1ad by port Media Access Control (MAC) Destination Address (DA), Virtual Local Area Network (VLAN) IDs, and the like, and in the case of 802.1Qay by the Backbone Service Instance Identifier (I-SID) with the Provider Backbone Bridge with Traffic Engineering (PBB-TE) trunk, which in turn is identified by the three-tuple of the Backbone Source Address (B-SA), Backbone Destination Address (B-DA) and the Backbone VLAN Identifier (B-VID). Currently, to provision a PW requires the underlying tunnel information to also be provisioned. However, some of the underlying tunnel attributes are associated with the hardware (HW) rather than with the PW service (e.g., port MAC address is a HW specific attribute). So if a physical line card (LC) 108 is replaced on the head end 104, the MAC address associated with the LC 108 changes and, therefore, the underlying tunnel is no longer valid and must be re-provisioned at the far-end NTE 102. For example, replacing LCs 108 is common in the network 100 for a variety of reasons, e.g. failures, upgrades, and the like.
Disadvantageously, this is cumbersome for network operators for the following reasons: network operators do not want to provision MAC addresses across their network, i.e. operators are used to MAC learning in layer two networks that do not require MAC address provisioning; when the LC 108 HW is changed, the technician changing the HW is not necessarily the right person to re-configure the PW service again; provisioning of far-end HW attributes leads to complex interdependencies and therefore misconfiguration errors; and there could be numerous (e.g., thousands) of PW services, causing significant scalability issues at an Element Management System 110.
Advantageously, network operators would find it useful to extend CFM and the like to distribute various service attributes to end points, such as, the attributes associated with PWs and other service constructs associated with a given tunnel Maintenance Endpoint Group (MEG).